Various antitheft devices of the aforesaid type are known. In general, these devices comprise gearshift locking members which both when in their utilization position (antitheft device engaged) and when in their rest position (antitheft device disengaged) are visible within the passenger compartment, to the detriment of its appearance. Other known antitheft devices comprise removable bars which are fixed to the handbrake lever and cooperate with the gear lever to prevent its use.
These devices are generally laborious to mount and often laborious to use.
Other antitheft devices of the aforesaid type are known which are incorporated in a concealed manner within the gearshift protection part.
One of these devices is described in BE-A-898020; this document describes an antitheft device to be mounted to the side of the gear lever and comprising a part fixed to the frame and a part movable relative to this latter to come into contact with the gear lever to lock it in a working position (with a gear engaged). The fixed part acts as a guide for the movable part or member, which is acted upon by a lever mechanism operated by a key. The lever mechanism carries at its end a pin movable within a guide provided transversely within the movable member, said lever mechanism being positioned parallel to said member when not cooperating with the gear lever, and having its longitudinal axis inclined (by an angle less than 90.degree.) to the longitudinal axis of said member when this latter cooperates with said gear lever to lock it.
The movable member is also provided at a rounded end with a seat in which the gear lever can sit when locked. This member is subjected to the action of a compression spring which tends to hold it still when cooperating with said gear lever, so locking it, and which opposes its release movement with a force exceeding that which can be exerted by the key. In this manner, said release is only possible by moving the movable member (by means of the key acting on the lever mechanism) and the gear lever simultaneously.
This known device has various drawbacks. Firstly, as it is positioned to the side of the gear lever it occupies a considerable space within the gearshift protection part. This prevents its use on automobiles in which this protection part is of small dimensions and where there is no space for positioning anything to the side of the gear lever.
In addition, the seat provided in the movable member is such as to enable the gear lever to be locked only when in certain particular positions (for example corresponding to first or third gear or possibly only reverse). Consequently for advantageous and reliable use of the antitheft device, the vehicle on which it is mounted has to be parked only in particular positions so that its unauthorized use can be prevented. For example, if the antitheft device is able to lock the gear lever when in the reverse gear position, for the vehicle not to be able to be moved it has to be parked with its rear end facing an obstacle (such as a wall).
Hence this Belgian device is hardly practical.
In addition, because the lever mechanism which moves the movable member is inclined to the axis of said member when this latter cooperates with the gear lever, by acting forcibly on the gear lever it is possible to move said member and release the gear lever. In this manner, if the gear lever is locked for example in the position corresponding to first gear, it can be released and shifted into neutral to enable the vehicle to be moved (for example removed from the obstacle in front of which it was parked). The gear lever can then be shifted into the position corresponding to first gear and the vehicle can be driven away.
In addition, this device is of considerable size and complicated construction. Finally, it is complicated to release the antitheft device, requiring manipulation both of the gear lever and of the key used to operate the lever mechanism which moves the movable member. This manipulation of the gear lever can lead with time to breakage of the pin by which movement is transmitted from the lever mechanism to the movable member.
Another device of the stated type is presented in WO-A-8804246, which describes an antitheft device acting on the gear lever and comprising two movable elements which close together about the gear lever, to lock it. This device has only one gear lever locking position, so limiting its reliable use. In addition, this device is of relatively large dimensions so preventing its universal use on any type of vehicle. Moreover the device is of complicated construction.